The Water Comes In - The Water Goes Out - Oops!

[hausdok]

Let's not forget the PEX and the plastic.

Click to Enlarge

Thanks to Charlie Sessums

Alpha Inspection

Jackson, MS

[Richard Moore]

OK...I'll start the debate. I realize the 2nd water heater in the series is hooked up backwards but, with both working, I do wonder if that's really an issue. Yes, they are drawing hot water from the bottom of the dip tube, but there would never be a slug of cold water down there like there might be in a single unit. I would suspect that it's been left that way because it hasn't been a problem. It's still wrong, and should be fixed, especially if they ever want to just use the second heater. But, in practical tems, how bad is it with both heaters on?

IRC allows PEX to be used as TPR piping so I would assume the same physics apply to the UPC. Are we concerned about the proximity to the draft hood?

[aaronm]

Even though PEX may be allowed by the IRC for TPR drain lines, I do not believe that direct connection of the PEX would be allowed. I currently have a request in to Zurn for an opinion.

Click to Enlarge

14.75 KB

[Terence McCann]

A.O. Smith's answer to series vs parallel piping.

http://www.hotwater.com/bulletin/bulletin64.pdf

[Tom Raymond]

Series plumbing only makes sense to me when there are multiple sources. My parent's have a gas boiler and an outdoor wood boiler, and the primary water heater is a heat exchanger zone on this system. Backup hot water comes from an 80 gallon gas water heater (second tank in the series). If the fuel is wood there is plenty of cheap hot water, but if the fuel is gas the 80 gallon tank is cheaper to operate than the boiler. This configuration has only one water heater running at any given time, more selectable than balanced.

Tom

[aaronm]

I got the word back from Zurn. They say it is OK to direct connect PEX to the TPR valve. Go figure.